An annular

solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season i ...

occurred at the Moon's

ascending node An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined. A non-inclined orbit, which is contained in the reference plane, has no nodes. Planes of reference Common planes of referenc ...

of orbit between Saturday, May 8 and Sunday, May 9, 1948, with a

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of 0.9999. A

occurs when the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

passes between

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

and the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's

apparent diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular separation (in units of angle) describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the '' visual ...

is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. The Moon's apparent diameter was near the average diameter because it occurred 7 days after

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

(on May 2, 1948, at 2:00 UTC) and 6.7 days before

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

(on May 15, 1948, at 17:10 UTC). The moon's apparent diameter was only 0.006% smaller than the Sun's, so this was an annular solar eclipse that occurred on May 9. The path width of this large annular solar eclipse, was about 200 meters and lasted only 0.3 seconds. The large annular eclipse covered over 99% of the Sun, creating a dramatic spectacle for observers in only an extremely narrow strip; however, it was fleeting, lasting just moments at the point of maximum eclipse. Annularity was visible from

Car Nicobar Car Nicobar ( in Car language) is the northernmost of the Nicobar Islands. It is also one of three local administrative divisions of the Indian district of Nicobar, part of the Indian union territory of Andaman and Nicobar Islands. Annual ra ...

, the northernmost of the

Nicobar Islands The Nicobar Islands are an archipelago, archipelagic island chain in the eastern Indian Ocean. They are located in Southeast Asia, northwest of Aceh on Sumatra, and separated from Thailand to the east by the Andaman Sea. Located southeast of t ...

, and

Burma Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and ha ...

, Siam (now renamed to

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

) including

Bangkok Bangkok, officially known in Thai language, Thai as Krung Thep Maha Nakhon and colloquially as Krung Thep, is the capital and most populous city of Thailand. The city occupies in the Chao Phraya River delta in central Thailand and has an estim ...

French Indochina French Indochina (previously spelled as French Indo-China), officially known as the Indochinese Union and after 1941 as the Indochinese Federation, was a group of French dependent territories in Southeast Asia from 1887 to 1954. It was initial ...

(the part now belonging to

Laos Laos, officially the Lao People's Democratic Republic (LPDR), is the only landlocked country in Southeast Asia. It is bordered by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the southeast, and Thailand to the west and ...

North Vietnam North Vietnam, officially the Democratic Republic of Vietnam (DRV; ; VNDCCH), was a country in Southeast Asia from 1945 to 1976, with sovereignty fully recognized in 1954 Geneva Conference, 1954. A member of the communist Eastern Bloc, it o ...

(now belonging to

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

Rebun Island is an island in the Sea of Japan off the northwestern tip of Hokkaidō, Japan. The island sits off the coast of Hokkaidō. Rebun stretches from north to south and from east to west. The island covers approximately . Rebun Island is located ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Kuril Islands The Kuril Islands or Kurile Islands are a volcanic archipelago administered as part of Sakhalin Oblast in the Russian Far East. The islands stretch approximately northeast from Hokkaido in Japan to Kamchatka Peninsula in Russia, separating the ...

in the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

(now belonging to

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

) on May 9, and

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

on May 8. A partial eclipse was visible for parts of

South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

Northeast Asia Northeast Asia or Northeastern Asia is a geographical Subregion#Asia, subregion of Asia. Its northeastern landmass and islands are bounded by the Pacific Ocean, North Pacific Ocean. The term Northeast Asia was popularized during the 1930s by Ame ...

, and northwest

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

. This was the first of four central solar eclipses visible from Bangkok from 1948 to

1958 Events January * January 1 – The European Economic Community (EEC) comes into being. * January 3 – The West Indies Federation is formed. * January 4 ** Edmund Hillary's Commonwealth Trans-Antarctic Expedition completes the thir ...

, where it is extremely rare for a large city to witness four central solar eclipses within 10 years.

Observations

During this eclipse, the apex of the moon's umbral cone was very close to the Earth's surface, and the magnitude was very large. The edges of the moon and the sun were very close to each other as seen from the Earth.

Baily's beads The Baily's beads, diamond ring or more rarely double diamond ring effects, are features of total and annular solar eclipses. Although caused by the same phenomenon, they are distinct events during these types of solar eclipses. As the Moon cover ...

on the

lunar limb The lunar limb is the edge of the visible surface (disc) of the Moon as viewed from Earth. Seen from afar, it looks like a circular arc, but with higher resolution, it can be seen that the Moon’s surface is not flat and therefore its profile is ...

, which are usually only visible during a total solar eclipse, could also be seen. Therefore this eclipse was also an excellent opportunity to measure the size and shape of the Earth, as well as the mountains and valleys on the lunar limb. The

National Geographic Society The National Geographic Society, headquartered in Washington, D.C., United States, is one of the largest nonprofit scientific and educational organizations in the world. Founded in 1888, its interests include geography, archaeology, natural sc ...

sent 7 teams respectively to Myeik in Burma, Bangkok in Siam, Wukang County (now belonging to Deqing County, Zhejiang) in China, of (now

Onyang-dong Onyang-dong, actually a series of six ''dong'', is the central and most populous part of the city of Asan in Chungcheongnam-do, South Korea. Geography Onyang-dong lies in the centre of Asan, 10 km south-west of Cheonan. It is bordered by Ye ...

Asan Asan (; ) is a Administrative divisions of South Korea, city in South Chungcheong Province, South Korea. It borders the Seoul Capital Area to the north. Asan has a population of approximately 400,000. Asan is known for its many hot springs an ...

City) in South Korea, Rebun Island in Japan,

Adak Island Adak Island (, ; ) or Father Island is an island near the western extent of the Andreanof Islands group of the Aleutian Islands in Alaska. Alaska's southernmost city, Adak, is located on the island. The island has a land area of , measuring lo ...

in Alaska, as well as from the air onboard a

Boeing B-29 Superfortress The Boeing B-29 Superfortress is a retired American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the Bo ...

departing from

Shemya Shemya or Simiya () is a small island in the Semichi Islands group of the Near Islands chain in the Aleutian Islands archipelago southwest of Alaska, at . It has a land area of , and is about southwest of Anchorage, Alaska. It is wide and long ...

Island. The scale of this observation was larger than ever before. In the end, the teams from the air and on Rebun Island got the best results with good weather conditions, while the results in Myeik and Bangkok were relatively good, Adak Island still somewhat valuable, Onyang-eup missing many goals, and Wukang with the worst results where there was rain during the eclipse. It was shortly after the end of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, and the observation in Japan showed friendship among the science community. , one of the two villages on the island, supported the observation team, and a Solar Eclipse Observation Monument was built in 1954 to commemorate it. The monument was first erected in Kitousu, the center of the observation site. It was moved to Itsukushima Shrine in 2003, across the sea facing Rishirifuji. Prior to it, the two hybrid solar eclipses of April 17, 1912 and April 28, 1930, also belonging to Solar Saros 137, also occurred with a magnitude close to 1. Observations were made near

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

and Camptonville, California respectively. There was an opportunity to make similar observations during the annular solar eclipse of May 20, 1966 in

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

and

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

, also belonging to the same solar Saros cycle. The Institute of Astronomy of the

Academia Sinica Academia Sinica (AS, ; zh, t=中央研究院) is the national academy of the Taiwan, Republic of China. It is headquartered in Nangang District, Taipei, Nangang, Taipei. Founded in Nanjing, the academy supports research activities in mathemat ...

(predecessor of

Purple Mountain Observatory The Purple Mountain Observatory (), also known as Zijinshan Astronomical Observatory, is an astronomical observatory located on the Purple Mountain in the east of Nanjing. The observatory is responsible for calculating the official Chinese calen ...

), Department of Physics of

National Central University National Central University (; abbreviated NCU; ) is a public research university based in Taiwan. It was founded in 1902 in Nanjing; initially located in Miaoli after moving to Taiwan, it relocated to Zhongli in 1962 and developed into a com ...

and Bureau of Surveying of the

Ministry of National Defense A ministry of defence or defense (see spelling differences), also known as a department of defence or defense, is the part of a government responsible for matters of defence and military forces, found in states where the government is divide ...

also formed a team. The initial plan was to go to

Guangdong ) means "wide" or "vast", and has been associated with the region since the creation of Guang Prefecture in AD 226. The name "''Guang''" ultimately came from Guangxin ( zh, labels=no, first=t, t= , s=广信), an outpost established in Han dynasty ...

, far from the observation site of the American team, hoping that the two teams would not be affected by bad weather at the same time. However after checking the weather, traffic and law and order conditions near

Guangzhou Guangzhou, Chinese postal romanization, previously romanized as Canton or Kwangchow, is the Capital city, capital and largest city of Guangdong Provinces of China, province in South China, southern China. Located on the Pearl River about nor ...

Hangzhou Hangzhou, , Standard Mandarin pronunciation: ; formerly romanized as Hangchow is a sub-provincial city in East China and the capital of Zhejiang province. With a population of 13 million, the municipality comprises ten districts, two counti ...

and

Suzhou Suzhou is a major prefecture-level city in southern Jiangsu province, China. As part of the Yangtze Delta megalopolis, it is a major economic center and focal point of trade and commerce. Founded in 514 BC, Suzhou rapidly grew in size by the ...

, the team finally decided on Cibiwu in

Yuhang County Yuhang is a suburban districtof Hangzhou, Zhejiang, China. On April 9, 2021, Linping District was established, consisting of the former Yuhang subdistricts of Linping, Donghu, Nanyuan, Xingqiao, Yunhe, Qiaosi, Chongxian and the Town of ...

. The decision was made based on the fact that meteorological data showed bad conditions generally across the whole

Jiangnan Jiangnan is a geographic area in China referring to lands immediately to the south of the lower reaches of the Yangtze River, including the southern part of its delta. The region encompasses the city of Shanghai, the southern part of Jiangsu ...

in May, within the

East Asian rainy season The East Asian rainy season (), also called the plum rain, is caused by precipitation along a persistent stationary front known as the Meiyu front for nearly two months during the late spring and early summer in East Asia between China, Taiwan ...

, and funding is limited so travel could not be made for a long distance. Besides, Xujiahui (Zi-Ka-Wei) Observatory estimated that there was 70% hope in Cibiwu, and it is close to the observation site of the American team, allowing the Chinese team to see the equipment of the American team for future reference. Zhang Yuzhe, director of the Institute of Astronomy, visited the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and

to study the

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

eclipsing binaries A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

in 1946. However, the Ministry of Foreign Affairs of the Republic of China stopped funding him the return trip back to China. He took the opportunity of joining the observation team to return to China in March 1948, and observed it together with . In the end, due to the weather conditions, just like the American team which traveled to China, the Chinese team also only measured changes in the luminosity of the sun. The Qingdao Observatory,

Sun Yat-sen University Sun Yat-sen University (; SYSU) is a public university in Guangzhou, Guangdong, China. It is affiliated with the Ministry of Education, and co-funded by the Ministry of Education, SASTIND, and Guangdong Provincial Government. The university is p ...

Observatory and the Department of Physics of

Tongji University Tongji University is a public university located in Shanghai, China. It is affiliated with the Ministry of Education of China. The university is part of Project 211, Project 985, and the Double First-Class Construction. Tongji is one of the ...

also made observations.

Eclipse details

Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.

Eclipse season

This eclipse is part of an

eclipse season An eclipse season is a period, roughly every six months, when eclipses occur. Eclipse seasons are the result of the axial parallelism of the Orbit of the Moon, Moon's orbital plane (orbital inclination, tilted five degrees to the ecliptic, Earth ...

, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a

fortnight A fortnight is a unit of time equal to 14 days (two weeks). The word derives from the Old English term , meaning "" (or "fourteen days", since the Anglo-Saxons counted by nights). Astronomy and tides In astronomy, a ''lunar fortnight'' is hal ...

Related eclipses

Eclipses in 1948

* A partial lunar eclipse on April 23. * An annular solar eclipse on May 9. * A penumbral lunar eclipse on October 18. * A total solar eclipse on November 1.

Metonic

* Preceded by:

Solar eclipse of July 20, 1944 An annular solar eclipse occurred at the Moon's ascending node of orbit on Thursday, July 20, 1944, with a magnitude of 0.97. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of t ...

* Followed by: Solar eclipse of February 25, 1952

Tzolkinex

* Preceded by: Solar eclipse of March 27, 1941 * Followed by: Solar eclipse of June 20, 1955

Half-Saros

* Preceded by: Lunar eclipse of May 3, 1939 * Followed by: Lunar eclipse of May 13, 1957

Tritos

* Preceded by: Solar eclipse of June 8, 1937 * Followed by: Solar eclipse of April 8, 1959

Solar Saros 137

* Preceded by: Solar eclipse of April 28, 1930 * Followed by: Solar eclipse of May 20, 1966

Inex

* Preceded by:

Solar eclipse of May 29, 1919 A total solar eclipse occurred at the Moon's descending node of orbit on Thursday, May 29, 1919, with a magnitude of 1.0719. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of ...

* Followed by: Solar eclipse of April 18, 1977

Triad

* Preceded by: Solar eclipse of July 8, 1861 * Followed by: Solar eclipse of March 9, 2035

Solar eclipses of 1946–1949

Saros 137

Metonic series

Tritos series

Inex series

Notes

References

{{Solar eclipses 1948 5 9 1948 in science 1948 5 9 May 1948